Plasma erosion resistant rare-earth oxide based thin film coatings

ABSTRACT

An article comprises a body and at least one protective layer on at least one surface of the body. The at least one protective layer is a thin film having a thickness of less than approximately 20 microns that comprises a ceramic selected from a group consisting of Y 3 Al 5 O 12 , Y 4 Al 2 O 9 , Er 2 O 3 , Gd 2 O 3 , Er 3 Al 5 O 12 , Gd 3 Al 5 O 12  and a ceramic compound comprising Y 4 Al 2 O 9  and a solid-solution of Y 2 O 3 —ZrO 2 .

RELATED APPLICATIONS

This patent application is a continuation application of U.S. patentapplication Ser. No. 14/306,583 filed Jun. 17, 2014, which claims thebenefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No.61/837,595, filed Jun. 20, 2013. application Ser. No. 14/306,583 isincorporated by reference herein.

TECHNICAL FIELD

Embodiments of the present invention relate, in general, to chambercomponents having a thin film plasma resistant protective layer.

BACKGROUND

In the semiconductor industry, devices are fabricated by a number ofmanufacturing processes producing structures of an ever-decreasing size.Some manufacturing processes such as plasma etch and plasma cleanprocesses expose a substrate to a high-speed stream of plasma to etch orclean the substrate. The plasma may be highly corrosive, and may corrodeprocessing chambers and other surfaces that are exposed to the plasma.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that differentreferences to “an” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

FIG. 1 depicts a sectional view of one embodiment of a processingchamber.

FIGS. 2A-5 depict cross sectional side views of example articles withprotective layer stacks on one surface.

FIG. 6 illustrates one embodiment of a process for forming one or moreprotective layers over an article.

FIG. 7A depicts a deposition mechanism applicable to a variety ofdeposition techniques utilizing energetic particles such as ion assisteddeposition (IAD).

FIG. 7B depicts a schematic of an IAD deposition apparatus.

FIGS. 8-9 illustrate erosion rates for thin film protective layersformed in accordance with embodiments of the present invention.

FIGS. 10-11 illustrate roughness profiles for thin film protectivelayers formed in accordance with embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present invention provide an article such as achamber component for a processing chamber having a thin film protectivelayer on one or more surfaces of the article. The protective layer mayhave a thickness below approximately 20 microns, and may provide plasmacorrosion resistance for protection of the article. The protective layermay be formed on the article using ion assisted deposition (IAD) orphysical vapor deposition (PVD). The thin film protective layer may beused as a top coat over a thick film protective layer, which may havebeen formed using, for example, plasma spraying techniques. In someembodiments, a thin film protective layer stack comprising two or morethin film protective layers is formed on the article. In suchembodiments, each thin film protective layer may be formed by IAD or PVDand may be around 20 microns or less in thickness. The thin filmprotective layer may be Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂,Gd₃Al₅O₁₂, or a ceramic compound comprising Y₄Al₂O₉ and a solid-solutionof Y₂O₃—ZrO₂. The improved erosion resistance provided by the thin filmprotective layer may improve the service life of the article, whilereducing maintenance and manufacturing cost.

FIG. 1 is a sectional view of a semiconductor processing chamber 100having one or more chamber components that are coated with a thin filmprotective layer in accordance with embodiments of the presentinvention. The processing chamber 100 may be used for processes in whicha corrosive plasma environment is provided. For example, the processingchamber 100 may be a chamber for a plasma etcher or plasma etch reactor,a plasma cleaner, and so forth. Examples of chamber components that mayinclude a thin film protective layer include a substrate supportassembly 148, an electrostatic chuck (ESC) 150, a ring (e.g., a processkit ring or single ring), a chamber wall, a base, a gas distributionplate, a showerhead, a liner, a liner kit, a shield, a plasma screen, aflow equalizer, a cooling base, a chamber viewport, a chamber lid 104,and so on. The thin film protective layer, which is described in greaterdetail below, may include Y₃Al₅O₁₂ (YAG), Y₄Al₂O₉ (YAM), Er₂O₃, Gd₂O₃,Er₃Al₅O₁₂ (EAG), Gd₃Al₅O₁₂ (GAG) and/or a ceramic compound comprisingY₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂. The thin film protectivelayer may also include Y₂O₃ and Y₂O₃ based ceramics, Er₂O₃ basedceramics, Gd₂O₃ based ceramics, and other rare earth oxides.

The thin film protective layer may be an IAD or PVD coating applied overdifferent ceramics including oxide based ceramics, Nitride basedceramics and Carbide based ceramics. Examples of oxide based ceramicsinclude SiO₂ (quartz), Al₂O₃, Y₂O₃, and so on. Examples of Carbide basedceramics include SiC, Si—SiC, and so on. Examples of Nitride basedceramics include AN, SiN, and so on. IAD or PVD coating target materialcan be calcined powders, preformed lumps (e.g., formed by green bodypressing, hot pressing, and so on), a sintered body (e.g., having50-100% density), a machined body (e.g., can be ceramic, metal, or ametal alloy), or a pre-melt (100% density). The substrate can also bemetal substrates such as Al, Ti, stainless steel, or anodized Al.

As illustrated, the substrate support assembly 148 has a thin filmprotective layer 136, in accordance with one embodiment. However, itshould be understood that any of the other chamber components, such asthose listed above, may also include a thin film protective layer.

In one embodiment, the processing chamber 100 includes a chamber body102 and a showerhead 130 that enclose an interior volume 106. Theshowerhead may include a showerhead base and a showerhead gasdistribution plate. Alternatively, the showerhead 130 may be replaced bya lid and a nozzle in some embodiments. The chamber body 102 may befabricated from aluminum, stainless steel or other suitable material.The chamber body 102 generally includes sidewalls 108 and a bottom 110.Any of the showerhead 130 (or lid and/or nozzle), sidewalls 108 and/orbottom 110 may include a thin film protective layer.

An outer liner 116 may be disposed adjacent the sidewalls 108 to protectthe chamber body 102. The outer liner 116 may be fabricated and/orcoated with a thin film protective layer. In one embodiment, the outerliner 116 is fabricated from aluminum oxide.

An exhaust port 126 may be defined in the chamber body 102, and maycouple the interior volume 106 to a pump system 128. The pump system 128may include one or more pumps and throttle valves utilized to evacuateand regulate the pressure of the interior volume 106 of the processingchamber 100.

The showerhead 130 may be supported on the sidewall 108 of the chamberbody 102. The showerhead 130 (or lid) may be opened to allow access tothe interior volume 106 of the processing chamber 100, and may provide aseal for the processing chamber 100 while closed. A gas panel 158 may becoupled to the processing chamber 100 to provide process and/or cleaninggases to the interior volume 106 through the showerhead 130 or lid andnozzle. Showerhead 130 is used for processing chambers used fordielectric etch (etching of dielectric materials). The showerhead 130includes a gas distribution plate (GDP) 133 having multiple gas deliveryholes 132 throughout the GDP 133. The showerhead 130 may include the GDP133 bonded to an aluminum base or an anodized aluminum base 104. The GDP133 may be made from Si or SiC, or may be a ceramic such as Y₂O₃, Al₂O₃,YAG, and so forth.

For processing chambers used for conductor etch (etching of conductivematerials), a lid may be used rather than a showerhead. The lid mayinclude a center nozzle that fits into a center hole of the lid. The lidmay be a ceramic such as Al₂O₃, Y₂O₃, YAG, or a ceramic compoundcomprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂. The nozzle mayalso be a ceramic, such as Y₂O₃, YAG, or the ceramic compound comprisingY₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂. The lid, showerhead base 104,GDP 133 and/or nozzle may be coated with a thin film protective layer.

Examples of processing gases that may be used to process substrates inthe processing chamber 100 include halogen-containing gases, such asC₂F₆, SF₆, SiCl₄, HBr, NF₃, CF₄, CHF₃, CH₂F₃, F, NF₃, Cl₂, CCl₄, BCl₃and SiF₄, among others, and other gases such as O₂, or N₂O. Examples ofcarrier gases include N₂, He, Ar, and other gases inert to process gases(e.g., non-reactive gases). The substrate support assembly 148 isdisposed in the interior volume 106 of the processing chamber 100 belowthe showerhead 130 or lid. The substrate support assembly 148 holds thesubstrate 144 during processing. A ring 146 (e.g., a single ring) maycover a portion of the electrostatic chuck 150, and may protect thecovered portion from exposure to plasma during processing. The ring 146may be silicon or quartz in one embodiment.

An inner liner 118 may be coated on the periphery of the substratesupport assembly 148. The inner liner 118 may be a halogen-containinggas resist material such as those discussed with reference to the outerliner 116. In one embodiment, the inner liner 118 may be fabricated fromthe same materials of the outer liner 116. Additionally, the inner liner118 may be coated with a thin film protective layer.

In one embodiment, the substrate support assembly 148 includes amounting plate 162 supporting a pedestal 152, and an electrostatic chuck150. The electrostatic chuck 150 further includes a thermally conductivebase 164 and an electrostatic puck 166 bonded to the thermallyconductive base by a bond 138, which may be a silicone bond in oneembodiment. An upper surface of the electrostatic puck 166 is covered bythe thin film protective layer 136 in the illustrated embodiment. In oneembodiment, the thin film protective layer 136 is disposed on the uppersurface of the electrostatic puck 166. In another embodiment, the thinfilm protective layer 136 is disposed on the entire exposed surface ofthe electrostatic chuck 150 including the outer and side periphery ofthe thermally conductive base 164 and the electrostatic puck 166. Themounting plate 162 is coupled to the bottom 110 of the chamber body 102and includes passages for routing utilities (e.g., fluids, power lines,sensor leads, etc.) to the thermally conductive base 164 and theelectrostatic puck 166.

The thermally conductive base 164 and/or electrostatic puck 166 mayinclude one or more optional embedded heating elements 176, embeddedthermal isolators 174 and/or conduits 168, 170 to control a lateraltemperature profile of the support assembly 148. The conduits 168, 170may be fluidly coupled to a fluid source 172 that circulates atemperature regulating fluid through the conduits 168, 170. The embeddedisolator 174 may be disposed between the conduits 168, 170 in oneembodiment. The heater 176 is regulated by a heater power source 178.The conduits 168, 170 and heater 176 may be utilized to control thetemperature of the thermally conductive base 164, thereby heating and/orcooling the electrostatic puck 166 and a substrate (e.g., a wafer) 144being processed. The temperature of the electrostatic puck 166 and thethermally conductive base 164 may be monitored using a plurality oftemperature sensors 190, 192, which may be monitored using a controller195.

The electrostatic puck 166 may further include multiple gas passagessuch as grooves, mesas and other surface features, that may be formed inan upper surface of the puck 166 and/or the thin film protective layer136. The gas passages may be fluidly coupled to a source of a heattransfer (or backside) gas such as He via holes drilled in the puck 166.In operation, the backside gas may be provided at controlled pressureinto the gas passages to enhance the heat transfer between theelectrostatic puck 166 and the substrate 144.

The electrostatic puck 166 includes at least one clamping electrode 180controlled by a chucking power source 182. The electrode 180 (or otherelectrode disposed in the puck 166 or base 164) may further be coupledto one or more RF power sources 184, 186 through a matching circuit 188for maintaining a plasma formed from process and/or other gases withinthe processing chamber 100. The sources 184, 186 are generally capableof producing RF signal having a frequency from about 50 kHz to about 3GHz and a power of up to about 10,000 Watts.

FIGS. 2A-5 illustrate cross sectional side views of articles (e.g.,chamber components) covered by one or more thin film protective layers.Referring to FIG. 2A, at least a portion of a base or body 205 of anarticle 200 is coated by a thin film protective layer 208. The article200 may be a chamber component, such as a substrate support assembly, anelectrostatic chuck (ESC), a ring (e.g., a process kit ring or singlering), a chamber wall, a base, a gas distribution plate or showerhead, aliner, a liner kit, a shield, a plasma screen, a flow equalizer, acooling base, a chamber viewport, a chamber lid, and so on. The body 205of the article 200 may be a metal, a ceramic, a metal-ceramic composite,a polymer, or a polymer-ceramic composite.

Various chamber components are composed of different materials. Forexample, an electrostatic chuck may be composed of a ceramic such asAl₂O₃ (alumina), AlN (aluminum nitride), TiO (titanium oxide), TiN(titanium nitride) or SiC (silicon carbide) bonded to an anodizedaluminum base. Al₂O₃, AlN and anodized aluminum have poor plasma erosionresistance. When exposed to a plasma environment with a Fluorinechemistry and/or reducing chemistry, an electrostatic puck of anelectrostatic chuck may exhibit degraded wafer chucking, increased Heleakage rate, wafer front-side and back-side particle production andon-wafer metal contamination after about 50 radio frequency hours(RFHrs) of processing. A radio frequency hour is an hour of processing.

A lid for a plasma etcher used for conductor etch processes may be asintered ceramic such as Al₂O₃ since Al₂O₃ has a high flexural strengthand high thermal conductivity. However, Al₂O₃ exposed to Fluorinechemistries forms AlF particles as well as aluminum metal contaminationon wafers. Some chamber lids have a thick film protective layer on aplasma facing side to minimize particle generation and metalcontamination and to prolong the life of the lid. However, most thickfilm coating techniques have a long lead time. Additionally, for mostthick film coating techniques special surface preparation is performedto prepare the article to be coated (e.g., the lid) to receive thecoating. Such long lead times and coating preparation steps can increasecost and reduce productivity, as well as inhibit refurbishment.Additionally, most thick-film coatings have inherent cracks and poresthat might degrade on-wafer defect performance.

A process kit ring and a single ring are used to seal and/or protectother chamber components, and are typically manufactured from quartz orsilicon. These rings may be disposed around a supported substrate (e.g.,a wafer) to ensure a uniform plasma density (and thus uniform etching).However, quartz and silicon have very high erosion rates under variousetch chemistries (e.g., plasma etch chemistries). Additionally, suchrings may cause particle contamination when exposed to plasmachemistries. The process kit ring and single ring may also consist ofsintered ceramics such as YAG and or ceramic compound comprising Y₄Al₂O₉and a solid-solution of Y₂O₃—ZrO₂.

The showerhead for an etcher used to perform dielectric etch processesis typically made of anodized aluminum bonded to a SiC faceplate. Whensuch a showerhead is exposed to plasma chemistries including fluorine,AlF may form due to plasma interaction with the anodized aluminum base.Additionally, a high erosion rate of the anodized aluminum base may leadto arcing and ultimately reduce a mean time between cleaning for theshowerhead.

A chamber viewport (also known as an endpoint window) is a transparentcomponent typically made of quartz or sapphire. Various optical sensorsmay be protected by the viewport, and may make optical sensor readingsthrough the viewport. Additionally, a viewport may enable a user tovisually inspect or view wafers during processing. Both quartz andsapphire have poor plasma erosion resistance. As the plasma chemistryerodes and roughens the viewport, the optical properties of the viewportchange. For example, the viewport may become cloudy and/or an opticalsignal passing through the viewport may become skewed. This may impairan ability of the optical sensors to collect accurate readings. However,thick film protective layers may be inappropriate for use on theviewport because these coatings may occlude the viewport.

The examples provided above set forth just a few chamber componentswhose performance may be improved by use of a thin film protective layeras set forth in embodiments herein.

Referring back to FIG. 2A, a body 205 of the article 200 may include oneor more surface features, such as the mesa illustrated in FIG. 2A. Foran electrostatic chuck, surface features may include mesas, sealingbands, gas channels, helium holes, and so forth. For a showerhead,surface features may include a bond line, hundreds or thousands of holesfor gas distribution, divots or bumps around gas distribution holes, andso forth. Other chamber components may have other surface features.

The thin film protective layer 208 formed on the body 205 may conform tothe surface features of the body 205. As shown, the thin film protectivelayer 208 maintains a relative shape of the upper surface of the body205 (e.g., telegraphing the shapes of the mesa). Additionally, the thinfilm coating may be thin enough so as not to plug holes in theshowerhead or He holes in the electrostatic chuck. In one embodiment,the thin film protective layer 208 has a thickness of below about 20microns. In a further embodiment, the thin film protective layer has athickness of between about 0.5 microns to about 7 microns.

The thin film protective layer 208 is a deposited ceramic layer that maybe formed on the body 205 of the article 200 using an ion assisteddeposition (IAD) process or a physical vapor deposition (PVD) process.One example IAD process that may be performed is electron beam ionassisted deposition (EB-IAD). The IAD or PVD deposited thin filmprotective layer 208 may have a relatively low film stress (e.g., ascompared to a film stress caused by plasma spraying or sputtering). Therelatively low film stress may cause the lower surface of the body 205to be very flat, with a curvature of less than about 50 microns over theentire body for a body with a 12 inch diameter. The IAD or PVD depositedthin film protective layer 208 may additionally have a porosity that isless than 1%, and less than about 0.1% in some embodiments. Therefore,the IAD or PVD deposited protective layer is a dense structure, whichcan have performance benefits for application on a chamber component.Additionally, the IAD or PVD deposited protective layer 208 may bedeposited without first roughening the upper surface of the body 205 orperforming other time consuming surface preparation steps. Sinceroughening the body may reduce a breakdown voltage of the body 205, theability to apply the thin film protective layer 208 without firstroughening the body 205 may be beneficial for some applications (e.g.,for an electrostatic chuck).

Examples of ceramics that may be used to form the thin film protectivelayer 208 include Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂,or a ceramic compound comprising Y₄Al₂O₉ and a solid-solution ofY₂O₃—ZrO₂ (Y₂O₃—ZrO₂ solid solution). Other Er based and/or Gd basedplasma resistant rare earth oxides may also be used to form the thinfilm protective layer 208. In one embodiment, the thin film protectivelayer is YAG composed of 35 mol % Y₂O₃ and 65 mol % Al₂O₃. In anotherembodiment, the ceramic coating can be YAG composed of 30-40 mol % Y₂O₃and 60-70 mol % Al₂O₃. In one embodiment, the ceramic compound includes62.93 mol % Y₂O₃, 23.23 mol % ZrO₂ and 13.94 mol % Al₂O₃. In anotherembodiment, the ceramic compound can include Y₂O₃ in a range of 50-75mol %, ZrO₂ in a range of 10-30 mol % and Al₂O₃ in a range of 10-30 mol%. In other embodiments, other distributions may also be used for theceramic compound. Any of the aforementioned ceramics may include traceamounts of other materials such as ZrO₂, Al₂O₃, SiO₂, B₂O₃, Er₂O₃,Nd₂O₃, Nb₂O₅, CeO₂, Sm₂O₃, Yb₂O₃, or other oxides.

TABLE 1 Material properties for IAD deposited YAG, Er₂O₃, BAG andceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.Bulk Thin-film coating Property 92% Al₂O₃ Ceramic Compound YAG Er₂O₃ EAGBreakdown 363 2500 (5 μm 6800 (5 μm) 527 (5 μm 900 (5 μm Voltage (V)coating) coating) coating) Volume >0.01E16 4.1E16 11.3E16  Resistivity(Ω · cm) Dielectric 9.2 9.83 +/− 0.04 9.76 +/− 0.01 9.67 9.54  ConstantLoss Tangent    5E−4   4E−4   4E−4   4E−4  4E−4 Thermal 18 19.9 20.1 19.4  19.2  Conductivity (W/m-K) Roughness 8 Unchanged UnchangedUnchanged Unchanged (μin) Seal Band 8.66 OSB 8.5 OSB 8.43 OSB MesaHeights 7.44 ISB 7.33 ISB 5.69 ISB (μin) Adhesion N/A >28 >32    Over92% Al₂O₃ (MPa) Hermicity    <1E−6 1.2E−9  4.4E−10 5.5E−9 9.5E−10 (Heleak rate) (cm³/s) Hardness 12.14 7.825 8.5 5.009 9.057 (GPa) Wear Rate0.2 0.14 0.113 0.176 (nm/RFhr)

Table 1 shows material properties for a substrate of 92% Al₂O₃ (alumina)and for various thin film protective layers coating a substrate of 92%Al₂O₃. As shown, the alumina substrate has a breakdown voltage of 363Volts/mil (V/mil). In contrast, a 5 micron (μm) coating of the IADdeposited ceramic compound comprising Y₄Al₂O₉ and a solid-solution ofY₂O₃—ZrO₂ has a breakdown voltage of 2500 V (much more than thenormalized value of 363 Volts/mil for alumina). A 5 μm coating of theIAD deposited YAG has a breakdown voltage of 6800 V. A 5 μm coating ofthe IAD deposited Er₂O₃ has a breakdown voltage of 527 V. A 5 μm coatingof the IAD deposited EAG has a breakdown voltage of 900 V.

A volume resistivity of the alumina is around 0.01×10¹⁶ (0.01E16) Ω·cmat room temperature. A volume resistivity of the ceramic compound thinfilm protective layer is about 4.1E16 Ω·cm at room temperature, and avolume resistivity of the YAG thin film protective layer is about11.3E16 Ω·cm at room temperature.

A dielectric constant of the alumina is about 9.2, a dielectric constantof the ceramic compound thin film is about 9.83, a dielectric constantof the YAG thin film is about 9.76, a dielectric constant of the Er₂O₃thin film is about 9.67, and a dielectric constant of the EAG thin filmis about 9.54. A loss tangent of the alumina is about 5E-4, a losstangent of the ceramic compound thin film is about 4E-4, a loss tangentof the YAG thin film is about 4E-4, a loss tangent of the Er₂O₃ thinfilm is about 4E-4, and a loss tangent of the EAG thin film is about4E-4. A thermal conductivity of the alumina is about 18 W/m-K, a thermalconductivity of the ceramic compound thin film is about 19.9 W/m-K, athermal conductivity of the YAG thin film is about 20.1 W/m-K, a thermalconductivity of the Er₂O₃ thin film is about 19.4 W/m-K, and a thermalconductivity of the EAG thin film is about 19.2 W/m-K.

The alumina substrate may have a starting roughness of approximately 8microinches in one embodiment, and that starting roughness may beapproximately unchanged in all of the thin film protective layers.Feature heights such as inner seal band (ISB) mesa heights and outerseal band (OSB) mesa heights may also be approximately unchanged as aresult of deposition of any of the thin film protective layers, asshown. Adhesion strength of the thin film protective layers to thealumina substrate may be above 28 mega pascals (MPa) for the ceramiccompound thin film and above 32 MPa for the YAG thin film. Adhesionstrength may be determined by measuring the amount of force used toseparate the thin film protective layer from the substrate. Hermicitymeasures the sealing capacity that can be achieved using the thin filmprotective layer. As shown, a He leak rate of around 1E-6 cubiccentimeters per second (cm³/s) can be achieved using alumina, a He leakrate of around 1.2E-9 can be achieved using the ceramic compound, a Heleak rate of around 4.4E-10 can be achieved using YAG, a He leak rate ofaround 5.5E-9 can be achieved using Er₂O₃ and a He leak rate of around9.5E-10 can be achieved using EAG. Lower He leak rates indicate animproved seal. Each of the example thin film protective layers has alower He leak rate than the Al₂O₃ substrate.

Each of Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, and theceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂have a high hardness that may resist wear during plasma processing. Asshown, alumina has a Vickers hardness (5 Kgf) of around 12.14 Gigapascals (GPa), the ceramic compound has a hardness of around 7.825 GPa,YAG has a hardness of around 8.5 GPa, Er₂O₃ has a hardness of around5.009 GPa, and EAG has a hardness of around 9.057 GPa. A measured wearrate of alumina is around 0.2 nanometers per radio frequency hour(nm/RFhr), a wear rate of the ceramic compound is about 0.14 nm/RFhr, awear rate of Er₂O₃ is about 0.113 nm/RFhr, and a wear rate of EAG isabout 0.176 nm/RFhr.

Note that the Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, andthe ceramic compound may be modified such that the material propertiesand characteristics identified above may vary by up to 30% in someembodiments. Accordingly, the described values for these materialproperties should be understood as example achievable values. Theceramic thin film protective layers described herein should not beinterpreted as being limited to the provided values.

FIG. 2B illustrates a cross sectional side view of one embodiment of anarticle 250 having a body 255 coated by a thin film protective layer258. As shown, the body 255 may be devoid of features. In oneembodiment, the body 255 is polished prior to deposition of the thinfilm protective layer 258. Rather than having features in the body 255,features may be formed in the thin film protective layer 258. Forexample, the thin film protective layer 258 may be masked and thenetched or bead blasted to remove unmasked portions of the thin filmprotective layer 258. The features can also be formed by masking thesubstrate and then applying the thin coating. Formed features mayinclude mesas, channels, seal rings, exposed bond lines (e.g., of ashowerhead), and so forth. Additionally, holes may be drilled in thethin film protective layer, such as by laser drilling. If features areto be formed in the thin film protective layer 258, the thin filmprotective layer should preferably have a thickness that is great enoughto accommodate the features. For example, if 12 μm mesas are to beformed in the thin film protective layer, then the thin film protectivelayer 258 should have a thickness that is greater than 12 μm. In otherembodiments, some features may be formed in the body 255, and otherfeatures may be formed in the thin film protective layer 258.

FIG. 3 illustrates a cross sectional side view of one embodiment of anarticle 300 having a thick protective layer 330 and a thin filmprotective layer 308. The thick protective layer may be Y₃Al₅O₁₂,Y₄Al₂O₉, Y₂O₃, or the ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂. Other plasma resistant ceramics may also beused for the thick protective layer 330.

The thick protective layer 330 may be a thick film protective layer,which may have been thermally sprayed (e.g., plasma sprayed) onto thebody 305. An upper surface of the body 305 may be roughened prior toplasma spraying the thick film protective layer onto it. The rougheningmay be performed, for example, by bead blasting the body 305. Rougheningthe upper surface of the body provides anchor points to create amechanical bond between the plasma sprayed thick film protective layerand the body 305 for better adhesion. The thick film protective layermay have an as sprayed thickness of up to about 200 microns or thicker,and may be ground down to a final thickness of approximately 50 micronsin some embodiments. A plasma sprayed thick film protective layer mayhave a porosity of about 2-4%.

Alternatively, the thick protective layer 330 may be a bulk sinteredceramic that has been bonded to the body 305. The thick protective layer330 may be provided, for example, as a thin ceramic wafer having athickness of approximately 200 microns.

The thin film protective layer 308 may be applied over the thickprotective layer 330 using IAD or PVD. The thin film protective layer308 may act as a top coat, and may act as an erosion resistant barrierand seal an exposed surface of the thick protective layer 330 (e.g.,seal inherent surface cracks and pores in the thick protective layer330).

FIG. 4 illustrates a cross sectional side view of one embodiment of anarticle 400 having a thin film protective layer stack 406 deposited overa body 405 of the article 400. Each thin film protective layer 408, 410in the thin film protective layer stack 406 may be one of Y₃Al₅O₁₂(YAG), Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, and the ceramiccompound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂. In oneembodiment, the same ceramic material is not used for two adjacent thinfilm protective layers. However, in another embodiment adjacent layersmay be composed of the same ceramic.

FIG. 5 illustrates a cross sectional side view of another embodiment ofan article 500 having a thin film protective layer stack 506 depositedover a body 505 of the article 500. Article 500 is similar to article400, except that thin film protective layer stack 506 has four thin filmprotective layers 508, 510, 515, 518.

The thin film protective layer stacks (such as those illustrated) mayhave any number of thin film protective layers. The thin film protectivelayers in a stack may all have the same thickness, or they may havevarying thicknesses. Each of the thin film protective layers may have athickness of less than approximately 20 microns, and less thanapproximately 10 microns in some embodiments. In one example, a firstlayer 408 may have a thickness of 3 microns, and a second layer 410 mayhave a thickness of 3 microns. In another example, first layer 508 maybe a YAG layer having a thickness of 2 microns, second layer 510 may bea compound ceramic layer having a thickness of 1 micron, third layer 515may be a YAG layer having a thickness of 1 micron, and fourth layer 518may be a compound ceramic layer having a thickness of 1 micron.

The selection of the number of ceramic layers and the composition of theceramic layers to use may be based on a desired application and/or atype of article being coated. EAG and YAG thin film protective layersformed by IAD and PVD typically have an amorphous structure. Incontrast, the IAD and PVD deposited compound ceramic and Er2O3 layerstypically have a crystalline or nano-crystalline structure. Crystallineand nano-crystalline ceramic layers may generally be more erosionresistant than amorphous ceramic layers. However, in some instances thinfilm ceramic layers having a crystalline structure or nano-crystallinestructure may experience occasional vertical cracks (cracks that runapproximately in the direction of the film thickness and approximatelyperpendicular to the coated surface). Such vertical cracks may be causedby lattice mismatch and may be points of attack for plasma chemistries.Each time the article is heated and cooled, the mismatch in coefficientsof thermal expansion between the thin film protective layer and thesubstrate that it coats cause stress on the thin film protective layer.Such stress may be concentrated at the vertical cracks. This may causethe thin film protective layer to eventually peel away from thesubstrate that it coats. In contrast, if there are not vertical cracks,then the stress is approximately evenly distributed across the thinfilm. Accordingly, in one embodiment a first layer 408 in the thin filmprotective layer stack 406 is an amorphous ceramic such as YAG or EAG,and the second layer 410 in the thin film protective layer stack 406 isa crystalline or nano-crystalline ceramic such as the ceramic compoundor Er₂O₃. In such an embodiment, the second layer 410 may providegreater plasma resistance as compared to the first layer 408. By formingthe second layer 410 over the first layer 408 rather than directly overthe body 405, the first layer 408 acts as a buffer to minimize latticemismatch on the subsequent layer. Thus, a lifetime of the second layer410 may be increased.

In another example, each of the body, Y₃Al₅O₁₂ (YAG), Y₄Al₂O₉, Er₂O₃,Gd₂O₃, Er₃Al₅O₁₂, Gd₃Al₅O₁₂, and the ceramic compound comprising Y₄Al₂O₉and a solid-solution of Y₂O₃—ZrO₂ may have a different coefficient ofthermal expansion. The greater the mismatch in the coefficient ofthermal expansion between two adjacent materials, the greater thelikelihood that one of those materials will eventually crack, peel away,or otherwise lose its bond to the other material. The protective layerstacks 406, 506 may be formed in such a way to minimize mismatch of thecoefficient of thermal expansion between adjacent layers (or between alayer and a body 405, 505). For example, body 505 may be alumina, andEAG may have a coefficient of thermal expansion that is closest to thatof alumina, followed by the coefficient of thermal expansion for YAG,followed by the coefficient of thermal expansion for the compoundceramic. Accordingly, first layer 508 may be EAG, second layer 510 maybe YAG, and third layer 515 may be the compound ceramic in oneembodiment.

In another example, the layers in the protective layer stack 506 may bealternating layers of two different ceramics. For example, first layer508 and third layer 515 may be YAG, and second layer 510 and fourthlayer 518 may be the compound ceramic. Such alternating layers mayprovide advantages similar to those set forth above in cases where onematerial used in the alternating layers is amorphous and the othermaterial used in the alternating layers is crystalline ornano-crystalline.

In some embodiments, one of more of the layers in the thin filmprotective layer stacks 406, 506 are transition layers formed using aheat treatment. If the body 405, 505 is a ceramic body, then a hightemperature heat treatment may be performed to promote interdiffusionbetween a thin film protective layer and the body. Additionally, theheat treatment may be performed to promote interdiffusion betweenadjacent thin film protective layers or between a thick protective layerand a thin film protective layer. Notably, the transition layer may be anon-porous layer. The transition layer may act as a diffusion bondbetween two ceramics, and may provide improved adhesion between theadjacent ceramics. This may help prevent a protective layer fromcracking, peeling off, or stripping off during plasma processing.

The thermal treatment may be a heat treatment at up to about 1400-1600degrees C. for a duration of up to about 24 hours (e.g., 3-6 hours inone embodiment). This may create an interdiffusion layer between a firstthin film protective layer and one or more of an adjacent ceramic body,thick protective layer or second thin film protective layer. If theceramic body is Al₂O₃, and the protective layer is composed of acompound ceramic Y₄Al₂O₉ (YAM) and a solid solution Y₂-xZr_(x)O₃(Y₂O₃—ZrO₂ solid solution), then a Y₃Al₅O₁₂ (YAG) interface layer willbe formed. Similarly, a heat treatment will cause a transition layer ofEAG to form between Er₂O₃ and Al₂O₃. A heat treatment will also cause atransition layer of YAG to form between Y₂O₃ and Al₂O₃. A heat treatmentmay also cause GAG to form between Gd₂O₃ and Al₂O₃. A heat treatment ofyttria stabilized zirconia (YSZ) over Al₂O₃ can form a transition layerof the compound ceramic of Y₄Al₂O₉ (YAM) and a solid solutionY₂-xZr_(x)O₃. Other transition layers may be formed between otheradjacent ceramics.

FIG. 6 illustrates one embodiment of a process 600 for forming a thinfilm protective layer over a body of an article such as a chambercomponent. At block 605 of process 600, an article is provided. At block610, a determination is made of whether or not to deposit a thick filmprotective layer onto the article. If a thick film protective layer isto be formed, the method proceeds to block 615. Otherwise, the methodcontinues to block 620.

At block 615, a thermal spray process (e.g., a plasma spray process) isperformed to deposit a thick film protective layer onto the article.Prior to performing the thermal spray process, the body of the articlemay be roughened in some embodiments. The thick film protective layermay be any plasma resistant ceramic. Some examples of thick filmprotective layers include Y₃Al₆O₁₂, Y₄Al₂O₉, Y₂O₃, YSZ, or the ceramiccompound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂. After thethick film protective layer is formed, for some applications surfacefeatures are formed on a surface of the thick film protective layer. Forexample, if the article is an ESC, then mesas and He holes may beformed. In an alternative embodiment, a plasma resistant ceramic disc orother ceramic structure may be bonded to the body of the article ratherthan spraying a thick film protective layer.

At block 620, IAD or PVD is performed to deposit a thin film protectivelayer on the body of the article. If a thick film protective layer wasformed at block 615, then the thin film protective layer may be formedover the thick film protective layer as a top coat. The thin filmprotective layer may be Y₃Al₆O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₆O₁₂,Gd₃Al₆O₁₂, or the ceramic compound of Y₄Al₂O₉ and a solid-solution ofY₂O₃—ZrO₂. A deposition rate for the thin film protective layer may beabout 1-8 Angstroms per second, and may be varied by tuning depositionparameters. The thin film protective layers may be very conforming, maybe uniform in thickness, and have a good adhesion to the body/substratethat they are deposited on.

At block 625, a determination is made regarding whether to deposit anyadditional thin film protective layers. If an additional thin filmprotective layer is to be deposited, the process continues to block 630.At block 630, another thin film protective layer is formed over thefirst thin film protective layer. The other thin film protective layermay be composed of a ceramic that is different than a ceramic of thefirst thin film protective layer. In one embodiment, the other thin filmprotective layer is one of Y₃Al₆O₁₂, Y₄Al₂O₉, Er₂O₃, Gd₂O₃, Er₃Al₆O₁₂,Gd₃Al₆O₁₂, or the ceramic compound of Y₄Al₂O₉ and a solid-solution ofY₂O₃—ZrO₂. The method then returns to block 625. If at block 625 noadditional thin film protective layers are to be applied, the processends. After any of the thin film protective layers is deposited, surfacefeatures may be formed in that thin film protective layer.

FIG. 7A depicts a deposition mechanism applicable to a variety ofdeposition techniques utilizing energetic particles such as ion assisteddeposition (IAD). Exemplary IAD methods include deposition processeswhich incorporate ion bombardment, such as evaporation (e.g., activatedreactive evaporation (ARE)) and sputtering in the presence of ionbombardment to form plasma resistant coatings as described herein. Anyof the IAD methods may be performed in the presence of a reactive gasspecies, such as O₂, N₂, halogens, etc.

As shown, the thin film protective layer 715 is formed by anaccumulation of deposition materials 702 in the presence of energeticparticles 703 such as ions. The deposition materials 702 include atoms,ions, radicals, or their mixture. The energetic particles 703 mayimpinge and compact the thin film protective layer 715 as it is formed.

In one embodiment, IAD is utilized to form the thin film protectivelayer 715, as previously described elsewhere herein. FIG. 7B depicts aschematic of an IAD deposition apparatus. As shown, a material source750 provides a flux of deposition materials 702 while an energeticparticle source 755 provides a flux of the energetic particles 703, bothof which impinge upon the article 750 throughout the IAD process. Theenergetic particle source 755 may be an Oxygen or other ion source. Theenergetic particle source 755 may also provide other types of energeticparticles such as inert radicals, neutron atoms, and nano-sizedparticles which come from particle generation sources (e.g., fromplasma, reactive gases or from the material source that provide thedeposition materials). The material source (e.g., a target body) 750used to provide the deposition materials 702 may be a bulk sinteredceramic corresponding to the same ceramic that the thin film protectivelayer 715 is to be composed of. For example, the material source may bea bulk sintered ceramic compound body, or bulk sintered YAG, Er₂O₃,Gd₂O₃, Er₃Al₅O₁₂, or Gd₃Al₅O₁₂. IAD may utilize one or more plasmas orbeams to provide the material and energetic ion sources. Reactivespecies may also be provided during deposition of the plasma resistantcoating. In one embodiment, the energetic particles 703 include at leastone of non-reactive species (e.g., Ar) or reactive species (e.g., O). Infurther embodiments, reactive species such as CO and halogens (Cl, F,Br, etc.) may also be introduced during the formation of a plasmaresistant coating to further increase the tendency to selectively removedeposited material most weakly bonded to the thin film protective layer715.

With IAD processes, the energetic particles 703 may be controlled by theenergetic ion (or other particle) source 755 independently of otherdeposition parameters. According to the energy (e.g., velocity), densityand incident angle of the energetic ion flux, composition, structure,crystalline orientation and grain size of the thin film protective layermay be manipulated. Additional parameters that may be adjusted are atemperature of the article during deposition as well as the duration ofthe deposition. The ion energy may be roughly categorized into lowenergy ion assist and high energy ion assist. The ions are projectedwith a higher velocity with high energy ion assist than with low energyion assist. In general superior performance has been shown with highenergy ion assist. Substrate (article) temperature during deposition maybe roughly divided into low temperature (around 120-150° C. in oneembodiment which is typical room temperature) and high temperature(around 270° C. in one embodiment).

TABLE 2 Example Thin Film Protective Layers Formed Using IAD ThicknessDep. Rate Ion Temp. He leak rate Hardness Material (μm) (A/s) Assist (°C.) XRD (cm³/s) (GPa) 1^(st) Compound 5 2 Low 270 C N/A 4.11 Ceramic2^(nd) 6 1 for 2 μm Low 270 C + A 5.0E−6 Compound 2 for 4 μm Ceramic3^(rd) Compound 5 1 Low 270 C + A 6.3E−6 Ceramic 4^(th) Compound 5 1 for1 μm High 270 A 1.2E−9 7.825 Ceramic 2 for 4 μm 5^(th) Compound 5 1 for1 μm High 120-150 A 1.2E−9 Ceramic 2 for 4 μm 1^(st) YAG 5 2.5 Low 270 A3.7E−7 5.7 2^(nd) YAG 5 1 for 1 μm High 270 A  4.4E−10 8.5 2 for 4 μmCompound 5 2 Low 270 C + A 3.7E−7 Ceramic/YAG 1^(st) Er₂O₃ 5 2 Low 270 C  3E−6 2^(nd) Er₂O₃ 5 1 for 1 μm High 270 C 5.5E−9 5.009 2 for 4 μm1^(st) EAG 7.5 1 for 1 μm High 270 A  9.5E−10 8.485 (calcined 2 for nextat 1700° C.) 2^(nd) EAG 7.5 1 for 1 μm High 120-150 A 2.5E−9 9.057(calcined at 2 for next 1600° C.)

Table 2 shows multiple example thin film protective layers formed usingIAD with various deposition parameters. Five different examples areshown for thin film protective layers formed from the ceramic compoundof Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂. A first example compoundceramic thin film protective layer has a thickness of 5 microns, and wasformed using IAD with a low energy ion assist, a deposition temperatureof 270° C., and a deposition rate of 2 angstroms per seconds (A/s).X-ray diffraction showed that the first example compound ceramic thinfilm protective layer had a crystalline structure. The first examplecompound ceramic thin film protective layer also had a hardness of 4.11GPa and visual inspection showed good conformance to the underlyingsubstrate as well as some vertical cracks and some spikes.

A second example compound ceramic thin film protective layer has athickness of 6 microns, and was formed using IAD with a low energy ionassist, a deposition temperature of 270° C., and a deposition rate of 1A/s for the first 2 microns and a deposition rate of 2 A/s for thesubsequent 4 microns. X-ray diffraction showed that the second examplecompound ceramic thin film protective layer had a nano-crystallinestructure (in which portions are crystalline and portions areamorphous). When used as a seal, the second example compound ceramicthin film protective layer was able to maintain a vacuum down to 5E-6cm³/s. Visual inspection of the second example compound ceramic thinfilm protective layer showed good conformance and fewer vertical cracksthan the first example compound ceramic thin film protective layer.

A third example compound ceramic thin film protective layer has athickness of 5 microns, and was formed using IAD with a low energy ionassist, a deposition temperature of 270° C., and a deposition rate of 1A/s. X-ray diffraction showed that the third example compound ceramicthin film protective layer had a nano-crystalline structure. When usedas a seal, the third example compound ceramic thin film protective layerwas able to maintain a vacuum down to 6.3E-6 cm³/s. Visual inspection ofthe third example compound ceramic thin film protective layer showedgood conformance and fewer vertical cracks than the first examplecompound ceramic thin film protective layer.

A fourth example compound ceramic thin film protective layer has athickness of 5 microns, and was formed using IAD with a high energy ionassist, a deposition temperature of 270° C., and a deposition rate of 1A/s for the first micron and 2 A/s for the subsequent 4 microns. X-raydiffraction showed that the third example compound ceramic thin filmprotective layer had an approximately amorphous structure. When used asa seal, the third example compound ceramic thin film protective layerwas able to maintain a vacuum down to 1.2E-9 cm³/s. Visual inspection ofthe fourth example compound ceramic thin film protective layer showedgood conformance, a smooth surface and very few vertical cracks.Additionally, the fourth example compound ceramic thin film protectivelayer has a hardness of 7.825 GPa.

A fifth example compound thin film protective layer was formed using thesame parameters as the fourth example compound thin film protectivelayer, but with a deposition temperature at room temperature (around120-150° C.). The fifth example compound thin film protective layershowed similar properties to those of the fourth example compound thinfilm protective layer.

A first example YAG thin film protective layer has a thickness of 5microns, and was formed using IAD with a low energy ion assist, adeposition temperature of 270° C., and a deposition rate of 2.5 A/s.X-ray diffraction showed that the first YAG ceramic thin film protectivelayer had an amorphous structure. The first YAG thin film protectivelayer also had a hardness of 5.7 GPa and visual inspection showed goodconformance, minimal cracking and a smooth surface.

A second example YAG thin film protective layer has a thickness of 5microns, and was formed using IAD with a high energy ion assist, adeposition temperature of 270° C., and a deposition rate of 1 A/s for afirst micron and 2 A/s for the subsequent 4 microns. X-ray diffractionshowed that the second YAG thin film protective layer had an amorphousstructure. The second YAG thin film protective layer also had a hardnessof 8.5 GPa and visual inspection showed good conformance, reducedcracking compared to the first YAG thin film and a smooth surface.

An example thin film protective layer stack with alternating compoundceramic and YAG layers has a thickness of 5 microns, and was formedusing IAD with a low energy ion assist, a deposition temperature of 270°C., and a deposition rate of 2 A/s. X-ray diffraction showed that thealternating layers were amorphous (for the YAG layers) and crystallineor nano-crystalline (for the compound ceramic layers). Visual inspectionshowed reduced vertical cracks for the compound ceramic layers.

A first example Er₂O₃ thin film protective layer has a thickness of 5microns, and was formed using IAD with a low energy ion assist, adeposition temperature of 270° C., and a deposition rate of 2 A/s. X-raydiffraction showed that the first Er₂O₃ ceramic thin film protectivelayer had a crystalline structure. Visual inspection showed goodconformance and a vertical cracking.

A second example Er₂O₃ thin film protective layer has a thickness of 5microns, and was formed using IAD with a high energy ion assist, adeposition temperature of 270° C., and a deposition rate of 1 A/s forthe first micron and a deposition rate of 2 A/s for the subsequent 4microns. X-ray diffraction showed that the second Er₂O₃ ceramic thinfilm protective layer had a crystalline structure. Visual inspectionshowed good conformance and a less vertical cracking compared to thefirst Er₂O₃ ceramic thin film protective layer.

A first example EAG thin film protective layer has a thickness of 7.5microns, and was formed using IAD with a high energy ion assist, adeposition temperature of 270° C., and a deposition rate of 1 A/s forthe first micron and a deposition rate of 2 A/s for the subsequentmicrons. X-ray diffraction showed that the first EAG ceramic thin filmprotective layer had an amorphous structure, and the layer had ahardness of 8.485 GPa. Visual inspection showed good conformance andminimal cracking.

A second example EAG thin film protective layer has a thickness of 7.5microns, and was formed using IAD with a high energy ion assist, adeposition temperature of 120-150° C., and a deposition rate of 1 A/sfor the first micron and a deposition rate of 2 A/s for the subsequentmicrons. X-ray diffraction showed that the second EAG ceramic thin filmprotective layer had an amorphous structure, and the layer had ahardness of 9.057 GPa. Visual inspection showed good conformance and aless cracking compared to the first EAG ceramic thin film protectivelayer.

FIGS. 8-9 illustrate erosion rates for thin film protective layersformed in accordance with embodiments of the present invention. FIG. 8shows erosion rates of thin film protective layers when exposed to aCH₄/Cl₂ plasma chemistry. As shown, the IAD deposited thin filmprotective layers show a much improved erosion resistance as compared toAl₂O₃. For example, alumina with a 92% purity showed an erosion rate ofaround 18 nanometers pre radiofrequency hour (nm/RFHr) and alumina witha 99.8% purity showed an erosion rate of about 56 nm/RFHr. In contrastan IAD deposited compound ceramic thin film protective layer showed anerosion rate of about 3 nm/RFHr and an IAD deposited YAG thin filmprotective layer showed an erosion rate of about 1 nm/RFHr.

FIG. 9 shows erosion rates of thin film protective layers when exposedto a H₂/NF₃ plasma chemistry. As shown, the IAD deposited thin filmprotective layers show a much improved erosion resistance as compared toAl₂O₃. For example, alumina with a 92% purity showed an erosion rate ofaround 190 nm/RFHr and alumina with a 99.8% purity showed an erosionrate of about 165 nm/RFHr. In contrast an IAD deposited YAG thin filmprotective layer showed an erosion rate of about 52 nm/RFHr. Similarly,a compound ceramic thin film protective layer deposited using IAD withlow energy ions showed an erosion rate of about 45 nm/RFHr and acompound ceramic thin film protective layer deposited using IAD withhigh energy ions showed an erosion rate of about 35 nm/RFHr. An EAG thinfilm protective layer deposited using IAD with high depositiontemperature (e.g., around 270° C.) showed an erosion rate of about 95nm/RFHr and an EAG thin film protective layer deposited using IAD withlow deposition temperature (e.g., around 120-150° C.) showed an erosionrate of about 70 nm/RFHr. An Er₂O₃ thin film protective layer depositedusing IAD with high energy ions showed an erosion rate of about 35nm/RFHr.

FIGS. 10-11 illustrate roughness profiles for thin film protectivelayers formed in accordance with embodiments of the present invention.FIG. 10 shows surface roughness profiles of thin film protective layersof FIG. 8 before and after exposure to a CH₄/Cl₂ plasma chemistry for100 RFHrs. As shown, the IAD deposited thin film protective layers showa minimum change in surface roughness after exposure to a CH₄/Cl₂ plasmachemistry for 100 RFHrs.

FIG. 11 shows surface roughness profiles of thin film protective layersof FIG. 9 before and after exposure to an H₂/NF₃ plasma chemistry for 35RFHrs. As shown, the IAD deposited thin film protective layers show aminimum change in surface roughness after exposure to an H₂/NF₃ plasmachemistry for 35 RFHrs.

The preceding description sets forth numerous specific details such asexamples of specific systems, components, methods, and so forth, inorder to provide a good understanding of several embodiments of thepresent invention. It will be apparent to one skilled in the art,however, that at least some embodiments of the present invention may bepracticed without these specific details. In other instances, well-knowncomponents or methods are not described in detail or are presented insimple block diagram format in order to avoid unnecessarily obscuringthe present invention. Thus, the specific details set forth are merelyexemplary. Particular implementations may vary from these exemplarydetails and still be contemplated to be within the scope of the presentinvention.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment” in various places throughout thisspecification are not necessarily all referring to the same embodiment.In addition, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” When the term “about” or “approximately” is usedherein, this is intended to mean that the nominal value presented isprecise within ±30%.

Although the operations of the methods herein are shown and described ina particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operation may be performed, at least in part,concurrently with other operations. In another embodiment, instructionsor sub-operations of distinct operations may be in an intermittentand/or alternating manner.

It is to be understood that the above description is intended to beillustrative, and not restrictive. Many other embodiments will beapparent to those of skill in the art upon reading and understanding theabove description. The scope of the invention should, therefore, bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

What is claimed is:
 1. An article comprising: a body; and a firstconformal protective layer on at least one surface of the body, whereinthe first conformal protective layer is a thin film having a thicknessof approximately 0.5-20 microns that comprises a first ceramic selectedfrom a group consisting of Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Er₃Al₅O₁₂,Gd₃Al₅O₁₂ and a ceramic compound comprising Y₄Al₂O₉ and a solid-solutionof Y₂O₃—ZrO₂.
 2. The article of claim 1, wherein the first conformalprotective layer comprises Er₂O₃, the first conformal protective layerhaving a crystalline structure with vertical cracks, a hardness ofapproximately 5 Gpa, a surface roughness that matches an underlyingsurface roughness of the at least one surface, and a hermiticity of atleast 5.5E-9 cm³/s.
 3. The article of claim 1, wherein the firstconformal protective layer comprises Er₃Al₅O₁₂, the first conformalprotective layer having an amorphous structure, a hardness ofapproximately 9 Gpa, a surface roughness that matches an underlyingsurface roughness of the at least one surface, and a hermiticity of atleast 9.5E-10 cm³/s.
 4. The article of claim 1, wherein: the articlecomprises a chamber component selected from a group consisting of achamber lid, a nozzle, a showerhead base, a showerhead gas distributionplate (GDP), a chamber viewport, a process kit ring, a shield, a plasmascreen, a flow equalizer, a chamber wall and a liner kit.
 5. The articleof claim 1, further comprising: a conformal protective layer stack onthe at least one surface of the body, the conformal protective layerstack comprising at least the first conformal protective layer and asecond conformal protective layer covering the first conformalprotective layer, wherein the second conformal protective layer has athickness of less than approximately 20 microns and comprises a secondceramic different from the first ceramic, the second ceramic selectedfrom the group consisting of: Y₃Al₅O₁₂, Y₄Al₂O₉, Er₂O₃, Er₃Al₅O₁₂, and aceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.6. The article of claim 5, wherein: the first conformal protective layerin the conformal protective layer stack has an amorphous structure andcomprises Y₃Al₅O₁₂ or Er₃Al₅O₁₂; and the second conformal protectivelayer in the conformal protective layer stack has a crystalline ornano-crystalline structure and comprises Er₂O₃ or the ceramic compoundcomprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂.
 7. The article ofclaim 5, wherein the body has a first coefficient of thermal expansionvalue, the first conformal protective layer has a second coefficient ofthermal expansion value, and the second conformal protective layer has athird coefficient of thermal expansion value, wherein the secondcoefficient of thermal expansion value is between the first coefficientof thermal expansion value and the third coefficient of thermalexpansion value.
 8. The article of claim 1, wherein the first conformalprotective layer comprises a plurality of surface features that are noton the at least one surface, the plurality of surface feature comprisingat least one of a mesa, a channel, or a seal ring.
 9. The article ofclaim 1, wherein the first conformal protective layer comprises theceramic compound comprising Y₄Al₂O₉ and a solid-solution of Y₂O₃—ZrO₂,and wherein the first conformal protective layer has an erosion rate ofabout 3 nm per hour of exposure to a CH₄/Cl₂ plasma chemistry and anerosion rate of about 35 nm per hour of exposure to an H₂/NF₃ plasmachemistry.
 10. The article of claim 1, wherein the article comprises aviewport of quartz or sapphire, and wherein the viewport and the firstprotective layer are transparent to optical signals transmitted throughthe viewport.
 11. The article of claim 1, wherein the first protectivelayer has a thickness of 0.5-7.0 microns.
 12. The article of claim 1,wherein the body has a diameter of at least 12 inches, and wherein theat least one surface of the body has a curvature of less than about 50microns over the body due to film stress associated with the firstprotective layer.
 13. The article of claim 1, wherein the at least onesurface comprises one of more first surface features that are also inthe first conformal protective layer, and wherein the first conformalprotective layer comprises one or more additional surface features thatare not on the at least one surface.
 14. The article of claim 1, whereinthe body comprises one or more holes, and wherein the first conformalprotective layer does not plug the one or more holes.
 15. The article ofclaim 1, wherein the conformal protective layer comprises Er₂O₃ and thebody comprises Al₂O₃, the article further comprising: a transition layerbetween the conformal protective layer and the body, wherein thetransition layer comprises Er₃Al₅O₁₂.
 16. The article of claim 1,wherein the conformal protective layer comprises yttrium stabilizedzirconia and the body comprises Al₂O₃, the article further comprising: atransition layer between the conformal protective layer and the body,wherein the transition layer comprises a compound ceramic of Y₄Al₂O₉ anda solid solution of Y₂O₃—ZrO₂.
 17. The article of claim 1, wherein thebody comprises at least one of Al₂O₃, AN, Al, anodized Al, Titanium,stainless steel, quartz, sapphire, Si or SiC.
 18. The article of claim1, further comprising: a second protective layer on at the least onesurface of the body, wherein the second protective layer is a thick filmhaving a thickness of greater than approximately 100 microns thatcomprises a second ceramic selected from a group consisting of Y₃Al₅O₁₂,Y₄Al₂O₉, Y₂O₃, and the ceramic compound comprising Y₄Al₂O₉ and asolid-solution of Y₂O₃—ZrO₂, wherein the first conformal protectivelayer covers the second protective layer.
 19. The article of claim 1,wherein a first roughness of the first conformal protective layer isapproximately the same as a second roughness of the body.
 20. Thearticle of claim 1, wherein the first conformal protective layer has anerosion resistance property that will cause it to change in averagesurface roughness (Ra) by not more than approximately 8μ in after 100hours of exposure to Ch₄/Cl₂ plasma chemistry.